Current-rectifying unit and method of preparing the same



May 1, 1928. 1,668,201

' E. R. GILL, SR

CURRENT RECTIFYING UNIT AND METHOD OF PREPARING THE SAME Filed Sept: 25.1926 ar -Iv" 1 I 15- 14 @i/ML K %L [2 anvewtoz 5 /1 L J awn Patented May1, 1928.

UNITED STATES EDWIN R. GILL, SR., OF YONKERS, NEW YORK.

dUBRENT-RECTIFYING UNIT ANI) METHOD OF PREPARING THE SAKE.

Application filed September 25, 1926. Serial No. 137,670.

The present invention has relation to the treatment of rectifyingcrystals, so called. whether natural or synthetic, whereby the slow andclumsy groping for the so-called sensitive spot is eliminated, making itpossible to instantly locate and distinguish by the eye the position,form and limits of the sensitive portions of any crystal or mass ofcrystals.

My invention also has reference to a complete mode of treatment andpreparation of rectifying units, as well as to the unit as complete i Inm applications for United States atent, led April 13th, 1926, SerialNumers 101,608 and 101,609 I have described a mode of preparingrectifying apparatus in volving what I have termed the develop- ,ment ofthe latent rectifying power of crystals whether natural or synthetic,and

in my United States application filed Au gust 13, 1926, Serial Number129,101, I have described a further advance in the art of developingthis latent power, together with a novel mode of preparing efficientrectifyin units.

These patentapplications had reference to the development or increase ofrectifying efficiency of these crystals under a conducting pointpreferably of silver, and the development as there described is carriedon under such aoint after the sensitive spot on the crysta is locatedand the conducting point is applied to it.

Hitherto it has been found necessary to grope blindly over the crystalsurface to nd the one or more sensitive spots on its surface by moving aconducting point or needle over said surface while observing thebehavior of a suitable current indicator in circuit with the needle andthe crystal. This is not'only a slow process, but, even when a sensitivespot-is found on a crystal, one cannot be sure that the best spot hasbeen located. Moreover it is frequently found that the crystal tested issubstan; tially worthless as a rectifier, and all the time spent in thusgroping over its surface proves to have been wasted. I

I have made the important discovery that, by a simple, rapid andinexpensive method of surface development analogous to the pointdevelopment above mentioned, all of the surfaces of acrystal mass may bemade to reveal to the eye the relative rectify ing powers of the variousportions exposed.

in question consists in moistening the surface with water or diluteacid, preferably the latter, while passing an electrical current throughthe same.

Inasmuch as I have had marked success with native iron pyrites, and asthe present invention relates partly to the finishing of a commercialrectifying unit, I shall hereinafter describe my process in itspreferred embodiment with reference to the preparation of a finishedunit made of pyritcs. It is to be understood, however, that my broadinvention is not limited either to this material or to this particularpurpose.

In the accompanying drawings Figures 1, 3 and 4 are perspective views ofa preferred form of rectifying unit in different stages of preparation,and Figure 2 is a diagram illustrative of the preferred process ofsurface development.

As already described in my earlier patent application, Serial Number129,101, I first cut out of a mass of pyritcs or its equivalent a cube,such as is shown in Figure l at 10. This will have a bright goldenglitter which is substantially uniform over the entire surface, as isindicated in Figure 1 by the absence of all shading between the outlinesof the cube. The eye cannot distinguish which portions, if any, of thesesurfaces are useful in rectification of an alternating current.

In' order to impart the surface development above mentioned I mayproceed as follows. A flat/plate 11, rcferably of carbon is moistened,preferab y with dilute sul-- phuric acid of the strength commonly usedin secondary battery cells and the cube 10 is set down upon it. The topof the cube then moistened in the same manner, and a flatflbottomedconductive'contact piece 12, preferably of carbon is laid on the cube.

- current.

At 13 and'14 are shown wires representing the two sides of anelectriccircuit. This may be either direct current or alternating I have alsoused direct superimposed upon alternating current. I find alternatingcurrent best for this purpose, however. The carbon plate 11 is laid upona metal plate 15 which is connected by the wire 16 to one side 14 of thecurrent supply, or any means may be employed to bring the plate 11 intocircuit. The wire 17 connects the carbon-contact piece 12 with theopposite wire 13.

\Vhile current is thus passing through the moistened surfaces of thecube 10, the surfaces of the conductors 11 and 12 may be vmade to rubacross the cube to insure uniform and efficient contact and to expeditethe process.

The amount of current used and the time employed will vary withcircumstances. With a cube of pyrites a quarter of an inch across I haveobtained excellent results with an alternating current of six volts bycontinuing the process for a few secondssay ten to twenty-five.

This step in the process being finished, the cube is carefully washedand preferably dried by evaporation, after which the proc- ,ess may berepeated until all six faces of the cube have been developed.

Figure 3 shows in a conventional form a picture that may be taken toroughly exemplify the appearance of the faces of the cube after thetreament above described; it being understood, of course, that in actualpractice the markings and shadings will var in form and locationindefinitely.

F or pur oses of example the sides of the cube have n represented inthree shades, pure white, light grey and dark grey. The pure white reresents a steely, hard surface which is brig t in appearance andconductive, but without appreciable rectifying power. There will also beobserved patches represented by the dark gre which are actu: ally uitedark and lack uster, somewhat resem ling soot. tain degree ofrectifyfing power, but they are very inferior to t ose parts of the surfaces conventionally shown in Figure 3 by the light grey shading.

These have a dull silvery aspect and invariably exhibit the maximum ofrectifying power. Of course, the sharp limits between these variousparts as shown in the figure are seldom found in practice. The varioussurfaces ma shade off into one another; but as a r'u e. the steelyrelatively useless portions are rather sharply defined.

\Vhen the entire cube has been developed in this way to make it revealits true properties to si ht, the various faces are in-' spected toetermine whlch will give the These portions have a cer-' rubbin on emercloth or otherwise grin ing. his has t ree uses. It increases theconductivity of these faces; it destroys any rectifying activity whichmight act counter to the effect desired from the chosen face; and itfits these faces. to be electroplated, preferably with copper.

This electro-plating is the next step, being accomplished in a wellknown manner; the

chosen active face being protected and ke t undisturbed and unrubbed sofar as possib e.

The finished unit is thus completed and presents the appearance shown inFigure 4, wherein the sides other than the active top are shown coveredwith a copper coating 17.

\Vhen this unit is placed in operative position under the conductingpoint which conveys current to it, a further point development may beobtained. which increases its efficiency. This is described in myearlier application Serial Number 129,101.

The process above described may be indefinitely varied and may beapplied to rectifying materials of various kinds in any stage of use andany condition without departing from my invention. It is also to eunderstood that the appartus herein described exemplifies merely theprinciples upon which commercial apparatus should be preferablyconstructed in carrying out my rocess.

W rat I claim is- 1. The process of treating the surface of a currentrectifying substance to make vis-.-

ible the more sensitive areas, which consists in moistening said surfaceand passing an electric current through said surface. i

2. v The process as in claim lwherein dilute sulphuric acid is used tomoisten the surface. v

3. The process as in claim 1 wherein two opposite surfaces are moistenedand current is passed through both.

4. The process as in claim 1 wherein alternating current is used.

5. he process of treating the surface of a current rectifying substanceto make visible the more sensitive areas which consists in moisteningthe surface and subjecting the same to friction while passing anelectric current there-through.

In testimony whereof I have hereto aflixed mgy signature on this 24thday of September, 1 6.

EDWIN R. GILL, SR.

